The use of Porro prisms of the 2nd type is known for binoculars from German patent publications 285,646; 288,468; and, 800,438. German patent publication 944,223 B discloses a Porro-like prism. U.S. Pat. No. 6,292,314 discloses the use of an Uppendahl prism.
In various optical systems, especially binoculars, the use of an Abbe-König prism system is known as, for example, in Zeiss Victory binocular 8×40 B T*.
An Abbe-König prism system is a reflection prism system via which an image is erected. A vertical reversal as well as a lateral reversal takes place. This prism system comprises two prisms which are cemented to each other or are arranged one behind the other at a small distance. An axis offset can be effected by the two prisms. The optical axis of the entry ray when entering into the Abbe-König prism system lies parallel to the optical axis of the exit beam from the Abbe-König prism system. When used in binoculars, the magnitude of the offset is typically 4 to 9 mm. The magnitude can be optimized in the optic design to a desired value, for example, between 0 and 10 mm.
Up to now, a light beam, especially a laser light beam has not been coupled in or coupled out because of the tight structural space of a modern slim binocular having Abbe-König prism systems and a folding bridge.